Many internal combustion engines utilize Gasoline Direct Injection (GDI) to increase the power efficiency and range over which the fuel can be delivered to the cylinder. GDI fuel injectors may require high pressure fuel for injection to create enhanced atomization for more efficient combustion. In many GDI applications a high-pressure fuel pump may be used to increase the pressure of fuel delivered to the fuel injectors. The high-pressure fuel pump may include a solenoid actuated “spill valve” (SV) or fuel volume regulator (FVR) that may be actuated to control flow of fuel into the high-pressure fuel pump. Throughout operation of the high-pressure fuel pump, actuation of the SV may generate noise/vibration/harshness (NVH).
In conventional vehicle systems, a method known as reduced solenoid current or “recur” is utilized to reduce the above described NVH. The recur method applies a predetermined low level of current to the SV that is just enough to initiate movement of the solenoid, after which the level of current supplied to the SV is promptly cut back to a hold current. Furthermore, complex feedforward and/or feedback control strategies including very high frequency processing rates based on measuring the current supplied to the SV are utilized to measure or determine the predetermined low level of current.
The inventors herein have recognized potential issues with this approach. Namely, there is a risk that the predetermined low level of current to the SV may fail to reliably initiate opening of the SV over a range of engine and fuel system conditions. Furthermore, equipping powertrain control modules (PCM's) with the circuitry for complex processing, including very high frequency processing rates, based on the supplied current to the SV is costly, and not possible for PCM's of some vehicle systems.
One approach that at least partially overcomes the above issues and achieves the technical result of reducing NVH associated with operation of the SV includes a method for operating a solenoid valve coupled to a direct injection fuel pump, comprising adjusting a pull-in electrical energy of the solenoid valve based on a fuel injection pump volumetric efficiency. In one example, such adjustments of the pull-in electrical energy are independent of sensed current of the SV. In this way, it is possible to improve system performance by providing sufficient SV current with feedback to enable maintenance of increased pump volumetric efficiency, while reducing NVH.
In another embodiment, a method of controlling fuel injection in a direct injection fuel system may comprise determining a pump volumetric efficiency of a fuel injection pump coupled to a solenoid valve, and in response to the determined pump volumetric efficiency, adjusting one or more of a valve pull-in current profile applied to the solenoid valve.
In another embodiment, a vehicle system may comprise an engine, a fuel system including a solenoid valve coupled to a fuel pump, the fuel system directly injecting fuel into the engine, and a controller, including instructions executable to adjust a valve pull-in current ramp rate of the solenoid valve based on an efficiency of the fuel pump, wherein the adjusting is performed only in response to the pump volumetric efficiency being less than a threshold pump volumetric efficiency.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.